def _count_ending_zeros_of_factorial(value: int):
    result = 0
    value = abs(value)
    while value > 0:
        value //= 5
        result += value
    return result


def _main():
    value = int(input("请输入一个数："))
    print(f"{value}! 的末尾有 {_count_ending_zeros_of_factorial(value)} 个零。")


if __name__ == "__main__":
    _main()
